The World Bank's chief economist for East Asia and the Pacific, Homi Kharas, says Avian flu is the "really big risk" that overshadows the region.
"There have been substantial outbreaks in poultry populations in a number of East Asian countries and although there have been relatively few human casualties so far, there is considerable concern that this particular strain of flu might mutate into one that could cause substantially higher human casualties and substantially higher economic costs as well," he said.
Mr. Kharas' comments were posted on the World Bank's Web site.
Earlier experience with the SARS illness shows a disease could quickly have an impact far outside the agriculture sector, damaging travel, tourism, trade, and many other industries.
The new World Bank report on emerging East Asia economies says the region has already had to cope with rising oil prices and changes in rules for textile exports. But Mr. Kharas says Asian nations have done "quite well" under the circumstances, posting a growth rate of just more than six percent in 2005.
The World Bank says the growth rate is likely to slow, but remain fairly strong, particularly in China.
The bank also said poverty is declining in most parts of East Asia.
This year, the number of people living on less than $2 a day fell to about 32 percent of the region's population. That is down from around 50 percent nine years ago.